RecordLayoutUtils.cpp

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//===--- RecordLayoutUtils.cpp - Shared record layout queries -------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#include "clang/CodeGenUtils/RecordLayoutUtils.h"
#include "clang/AST/RecordLayout.h"
#include "clang/Basic/TargetInfo.h"
 
namespace clang::CodeGenUtils {
 
bool hasOwnStorage(const ASTContext &Ctx, const CXXRecordDecl *Decl,
                   const CXXRecordDecl *Query) {
  const ASTRecordLayout &DeclLayout = Ctx.getASTRecordLayout(Decl);
  if (DeclLayout.isPrimaryBaseVirtual() && DeclLayout.getPrimaryBase() == Query)
    return false;
  for (const auto &Base : Decl->bases())
    if (!hasOwnStorage(Ctx, Base.getType()->getAsCXXRecordDecl(), Query))
      return false;
  return true;
}
 
bool isDiscreteBitFieldABI(const ASTContext &Ctx, const RecordDecl *RD) {
  return Ctx.getTargetInfo().getCXXABI().isMicrosoft() || RD->isMsStruct(Ctx);
}
 
bool isEmptyFieldForLayout(const ASTContext &Ctx, const FieldDecl *FD) {
  if (FD->isZeroLengthBitField())
    return true;
 
  if (FD->isUnnamedBitField())
    return false;
 
  return isEmptyRecordForLayout(Ctx, FD->getType());
}
 
bool isEmptyRecordForLayout(const ASTContext &Ctx, QualType T) {
  const auto *RD = T->getAsRecordDecl();
  if (!RD)
    return false;
 
  // If this is a C++ record, check the bases first.
  if (const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
    if (CXXRD->isDynamicClass())
      return false;
 
    for (const auto &I : CXXRD->bases())
      if (!isEmptyRecordForLayout(Ctx, I.getType()))
        return false;
  }
 
  for (const auto *I : RD->fields())
    if (!isEmptyFieldForLayout(Ctx, I))
      return false;
 
  return true;
}
 
bool isOverlappingVBaseABI(const ASTContext &Ctx) {
  return !Ctx.getTargetInfo().getCXXABI().isMicrosoft();
}
 
} // namespace clang::CodeGenUtils